The objective of this research is to understand how social interactions are translated into functional changes into the brain. Both androgens and glucocorticoids are known to modulate peptic gonadotropin (GnRH-I) neurons in this model system, the male teleost fish Haplochromis burtoni. However, the mechanisms through which these steroid hormones regulate GnRH-I expression are not known. The specific aims are: (1) To discover whether and how a change in social status affects the distribution and expression levels of brain androgen and glucocorticoid receptors, and to discover whether preoptic neurons of H. burtoni co-express androgen and/or glucocorticoid receptors along with GnRH-I. (2) To examine whether differences in social status regulated GnRH-I transcription. These experiments are important because they will provide a foundation for a molecular understanding of how social status and neuroendocrine feedback are integrated at a specific site through the control of a particular gene. By combining neuroanatomical and molecular analyses with manipulation of the animal's social status, these experiments all add significantly to our understanding of how hormonal information is integrated with social information at preoptic GnRH neurons. Since pre- optic GnRH neurons have been highly conserved throughout vertebrate evolution, discoveries in this model system could have far reaching applications in behavioral neuroendocrinology.